Electrical musical instrument



Feb. 14, 1961 W. J. ANDERSON v 2,971,420

ELECTRICAL MUSICAL INSTRUMENT 2 Sheets-Sheet 1 Filed March 14, 1958 wh ibm hm fnv wml mm IMU Nllwb el E f E Feb. 1'4, 1961 w. J. ANDERSON ELECTRICALMUSICAL INSTRUMENT 2 Sheets-Sheet 2 Filed March 14, 1958 United States Patent O ELECTRICAL MUSICAL INSTRUMENT Walter J. Anderson, Elgin, Ill., assigner to The Lowrey Organ Company, Chicago, Ill., a corporation of Illinois Filed Mar. 14, 195s, ser. No. 721,545

15 claims. (c1. sai-1.22).

This invention relates to musical instruments and more particularly to electric and electronic organs, and has for its primary `object the provision of new, improved and unique means for eliciting from a keyboard, musical sounds capable of exacting an auditory sensation of pitch and timbre typical of a much wider. range of musical instruments than heretofore possible with more costly instruments of the prior art. p

The tone frequency range and musical possibil-ities of electronic and electric organs is determined by the number of tone generators embodied in such instruments and the means employed for using the output signals thereof to produce musical sounds approximating the tone qualities of different musical instruments. If the instrument is moderately priced it is required either that the number of generators be reduced or that other methods and procedures be resorted to so as to reduce manufacturing costs. It has heretofore been impossible satisfactorily to attain this objective without loss of necessary musical possibilities. My invention not only overcomes preexisting manufacturing problems but, in addition thereto, contributes new and sought for advantages that make for vast improvement in the musical possibilities of such instruments.

A complex waveform produced by different types of tone `generators comprises partials or harmonics bearing the ratios 2n, 3n, 4n, Sn, etc. to the fundamental n. A simple illustration is a stretched string tuned to `a definite pitch and vibrating as a whole and, therefore, giving forth the lowest note which it is capable of producing. This note is called the fundamental of the string. When made to vibrate in two parts, the string gives forth a note an octave higher than the fundamental and is called the first partial. Similarly, the string can be placed in vibration to produce additional overtones bearing the ratios to the fundamental as above pointed to. In like manner, complex output tone signals of the various types of tone generators can be broken down into sensibly simple components. In the case of the instant invention it is required that the generator be capable of producing a complex output signal made up of an unbroken series of harmonies or partials that are integral multiples of the fundamental, such, for example, l, 2, 3, 4, 5, 6, 7, etc., each thereof being a `component of -a sound sensation which may be distinguished as a simple sound. A sawtooth wave produced by certain space `discharge devices employed as tone generators in electric organs; specially designed complex wave patterns or graphs in instruments employ-ing scanners and light sensitive devices as tone generators and numerous similar devices common in the art are examples of means that may be used in carrying the invention into practice.

The broad inventive concept of my invention finds expression ina new, novel and highly useful system or method for synthetically creating from sensibly simple components of electrically generated tone signals of complex waveform and given fundamental frequency musically useful signals of different'fundamental frequency lCC than the fundamentals of the complex waveforms of signals from which they are synthetically created, which waveforms thus created and the waveforms from which they were created are ladapted to be use'd in an electric, electronic or other keyboard musical instrument for producing tones at the frequencies of notes of the equal tempered musical scale.

Other objects are:

The provision of means in one exemplified embodiment of my invention for converting a complex tone signal of predetermined frequency into `a tone signal of simple waveform consisting of the fundamental of said complex signal, and creating from another complex signal having the same partial composition as the first named complex signal, a tone signal of simple waveform consisting of the first partial of said other complex signal, so that said simple waves produced as above stated have frequencies that are octavely related as notes of the same etter of the musical scale. i

The provision of means in another embodiment of my invention for synthetically creating from partial components of two octavely related complex tone signals, a third complex tone signal of sensibly the same wave pattern as said two complex tone signals, the fundamental of said third complex signal being an octave above one of said two complex signals and an `octave below the other thereof, such, for example, that the fundamentals of all three complex signals are to each other as are notes C2, C3 and C4 of the musical scale.

The invention will be better understood from the following description considered in connection with the accompanying drawings and its scope indicated by the appended claims.

Referring to the drawings:

Fig. l is a schematic View of one embodiment of my invention;

Fig. 2 is a similar view of another embodiment thereof; and

Fig. 3 is -a block diagram of a further embodiment of my invention.

In carrying `out my invention, reference is made to the block diagram, Fig. l, wherein an octave of tone generators C5-B5 is shown, said generators producing complex output waveforms, each comprising a` preassigned fundamental frequency and at least a iirst overtone component, which is the octave of said fundamental.

51 is a common collector in an output system comprising a mixer 52, amplifier 53 and loud speaker 54. Playing-key operated switches 1-6, inclusive, connect to the outputs of generators CS-FS respectively through paths 55u-55], inclusive, containing isolation resistors 56. Similar playing-key operated switches 7-12 inclusive connect to generators FitS-BS through paths SSg-SSI containing isolation resistors 5617. Thus, for this octave of generators there are two similar groups (six each) of playing-key operated switches. Switches 1-6, inclusive, connect to a common header 57 coupled to band pass wave filter A whose output side connects to junction point P through resistor 58, the junction point P connecting to the aforementioned mixer 52. The fundamental frequencies ofthe complex output waveforms from `generators CS-FS appearing at junction point P are of sinusoidal pattern, it being understood that filter A sensibly suppresses all upper partials of said complex output waveforms from generators CS-FS according as playingkey operated switches 1-6 are close-circuited.

Playing-key operated switches 7-12, inclusive, connect to common output header 59 which connects to bandpass wave filter B designed and adapted to pass only the fundamental frequencies of the complex output waveforms of generators F-S-BS and sensibly suppress all upper partial components of said fundamentals. 'Filter B connects to common collector 51 through isolation resistor 60.

To this point in the description of the exemplified embodiment of my invention shown at Fig. l of the accomrSwitches 13-18 connect to band pass wave filter C whose output side is coupled to collector S1 through isolation resistor 62. Similarly, switches 19-24, inclusive, connect to common header 75 which is coupled to band Vpanying drawings, all complex waveforms produced by 5 pass wave filter D, the youtput side of which connects generators C5-B5 are sensibly reduced to only their to collector 51 through resistor 76. Switches 13-18, infundamental frequencies and are of this simple tone ciusive, have respective paths 69-74 with isolation rewave pattern when arriving at junction point P so that sistors 56C that connect to generators CS-FS via paths when translated into sound waves, the auditory sensation 63-68 so that the complex output waveforms from said is that of mono-pitched sounds, such as those ofthe ute generators will be conducted to filter C according as and other musical sounds of simple wave pattern, i.e. switches 1343 are close-circuited. Filter C passes all sensibly free of upper partial components. In the temfirst harmonic frequencies in the complex output wavepered musical scale the fundamental frequency of note forms of said generators CS-FS and suppresses all other B5 is about 987.4- c.p.s. In electronic and electric frequencies of said waveforms, n so that, as explained organs employing keyboards not in excess of four full earlier with respect to filters A and B, the output freoctaves of notes, say from C2=65.l c.p.s. to B5 quencies of lter `C are sinusoidal. In like manner, play- =987.{- c.p.s., the frequency range is far too restricted ing-key operated switches 19-24 connect by paths 83-88 for the keenness of desired musical sounds for versatility to generators FttS-BS through isolation. resistors 56d and faithful simulation of many musical instruments, and paths '77-32 respectively. Said switches 19-24 consuch, for example, production of mixtures requiring 2O nect to header 75 which, in turn, connects to wave filter higher frequency components than are available in cases D having its output side connected to collector 51 where the frequency range is too limited because of the through resistor 76. Filter D passes all first harmonic number of actual tone generators employed. Then, too, frequencies of the output waveforms of generators FiiS* and in instruments employing means for controlling the B5' and sensibly suppresses all other partial components growth and decay of sounds as a function of time, it is of said waveforms, so that, as in the case of filter C, the necessary, for satisfactory musical results and close simuoutput frequencies of filter D are sensibly sinusoidal and lation of certain musical instruments, that a waveform form the second six note frequencies for said octave C6. of frequencies shall include a frequency high enough to The key grouping and filter system for conversion of make possible faithful duplication of characteristic complex waveforms of frequencies for one full octave timbres, particularly is this true in cases such as strings, of tones having substantially the vibration numbers of percussives, the iiute, oboe, clarinet, piccolo, etc. As tones in the scale of equal temperament into sinusoidal first above stated in the description of the primary purfundamental frequencies and for utilizing the first parpOse of my invention, the herein-disclosed method of tial (octave) components 4of said complex waveforms to producing a full octave of sinusoidal frequencies consists synthetically create a second full (higher octave) set of in synthetically creating a full higher octave of frequentone sources will be readily understood upon referring cies lfrom the first partial components of the complex to the following chart:

Generators Keys Complex Waves Filters Sine Waves C 1 523.| c.p.s A-Passes 523.-| eps g c.ps ....do c.p s C. S..- C. .S Key GOup No' 1 D#5 4 622+ ugs saai-@pis E5 5 659.-!- c.p s G59.-I-c.p.s F5 6 698.4- c p s 698:2- cps Octave F#5 7 739.| op s 739+ c.p.s No. 5 t sans c C S C. Kei Group No' 2 s- A 10 880.000 cpp 850.4- @.pl. M5 11 952.4- c p s ssa-|- ep. B5 12 987,-lc.p.s 987.4- c.p. C 13 Octave of C5 l04t`-.| op. s une C ZEVGO t C .S Key Gump No' 3 D 6 1G Octave ofD#5 1244-+ c.g.s

E 17 Octave of E.. 1318.4- c.p.s F6 18 Octave of F5 1396.-!- c.p.s Octave F#6 19 Octave of F# 1474.4- c.p.s No. 6 s serra f C BiVe 0 i` C. .S key Gloup No' 4 A 22 Octave of A5 17(i0.000 cI.)p.s A#6 23 Octave ofA#5 1864.4- c.p.s B6 24 Octave of B5 1975.+ c.p.s

waveforms (produced by actual generators) whose fundamentals are an octave lower than their said first partial components, then using these first partial components tok provide a higher octave of sensibly simple frequencies, which, in the instant case will be from 1046.4- c.p.s. to 1975+ c.p.s. as compared to from 523.-!- c.p\.s. to 987.+ c.p.s. (sensibly simple frequencies) iu the next preceding lower octave The audible frequency ofthe flute is about 4-80-2048 c.p.s. as compared with the range of frequencies obtainable from an octave of generators producing from 523.-{ c.p.s. to 987.-1- c.-p.s. as provided for herein, which obviously makes manifest the advantages derived from my invention, aside, entirely, from the fact that my invention effects substantial savings in manufacturing costs of such instruments.

Upon again referring to Fig. 1, there is shown a group of playing-key operated switches lS-iii, inclusive, and a similar group of playing-key operated switches 19--2-4.

Referring now to the exemplified form of my invention shown in block diagram at Fig'. 2 of the accompanying drawings, there is a full octave set of actual tone generators X comprising CZ-BZ generators producing a range of complex waveforms of from 65.{ c.p.s. to l23.-{- c.p.s., and a full octave set of generators Y, Csi-B4 producing frequencies ranging from 26l.-}- c.p.s. to 493.4- c.p.s. Thus these two octaves are broken by the absence of a set of actual C3 generators whose frequencics should be 130.4- c.p.s. to 246.4- c.p.s. It is this intermediate octave of complex waveforms which by the means constituting my invention are created from fundamental frequencies derived from generators (l2-B2 and from the complex waveforms of frequencies derived from generators Ci-Bs, thereby providing sources from which are available, complex waveforms of sensibly the same general wave pattern as the complex waveforms produced by the actual generators C22-B2 and Crt-B4,

the substantial difference being that of pitch of the fundamental frequencies. For the sake of simplification and to avoid confusion as would result from an otherwise complicated network, only four keying-circuits are shown as illustrative of the method of synthetically creating an octave of complex waveforms which are the sum' of frequencies taken from a lower octave set of actual tone generators and from a set of actual generators producing fundamental frequencies two octaves higher than said lower octave of generators.

Pointing now to the circuitry, Fig. 2, it sufiices to say that each generator assembly comprises octave sets of generators, each generator having an output path 90. Path 90 from generator C2 connects to a playing-key operated switch 91 having its fixed contact element connected to junction point P1, the latter connected to an output system comprising a mixer or timbre system 52o, audio amplifier 53a and loud speaker 54a. When switch 91 is close-circuited the complex output waveform C2 :65.-1- c.p.s. is conducted to junction point P1 and to said translating system. The complex pattern of the waveform is the same as the waveform of the signal produced by a respective generator C2. Thus the fundamental frequency of the complex waveform output of generator C2 4being 65.4- c.p.s., the first partial com- -ponent of said complex waveform is l30.-[ c.p.s., an

octave higher and, therefore, the fundamental of note C3.

Generator C4 produces a complex waveform whose fundamental is 260+ c.p.s., the octave of C3=130.-ic.p.s. Playing-key operated switch 92 has its movable contacter 93 connected by path 94 to output path 90 of generator C2, the fixed contact element 93A connecting to band pass wave filter 95 designed to pass only the first partial frequencies of CZ-FZ and suppress all other partial components. A band pass filter 96 is similarly connected to all outputs from generators FiZ-BZ, and, as shown, both said filters 95 and 96 connect at 97 to common collector 51a. It follows that the outputs of said filters 95 and 96 are each thereof a sinusoidal waveform 'whose frequency has the vibration rate of the second harmonic component of the complex waveform of a respective generator C2B2.

At 98 is a second playing-key operated switch consisting of a movable contacter 99 and a fixed contact element 160, the fixed contact element 100 connected by path 101 to collector 51a. Movable contact element 99 connects by path 102 to output path 102' of generator C4. Both switch contaotors 93 and 99 are common to a sticker 103 adapted to be simultaneously operated by playing-key 104 so that when depressing said key, the complex waveform from generator C2 is transmitted to filter 9S, which suppresses all frequency components except the first partial component of C2=l30 c.p.s. and, therefore, is the vibration rate of -note C3. Concurrently therewith, the lcomplex waveform from generator C4 is impressed on collector 51a. Consequently the sinusoidal fundamental frequency C3=l30 c.p.s. from filter 95, plus all frequencies of the C4 note, combine at the collector, with the result that there is synthetically created a complex wave form sensibly similar to the waveforms originating at the C2 and C4 octave of generators. It will be borne in mind that the fundamental frequency of note C4 is 260. c.p.s., the first harmonic of note C3.

While I have shown in complete detail twoI practical embodiments of my invention, it follows that from the disclosed method other combinations and arrangements are possible and clearly manifest to persons skilled in the art, such, for example, the arrangement and relationship of parts shown in block diagram in Figure 3, wherein blocks A, C and E are each thereof indicative of a full set of generators producing tone signals for a complete octave of notes, with blocks B and D interposed respectively between blocks A and C and C and E, blocks -B and D being indicative of the previously described means for synthetically creating ya full octave of tones for other notes following the sequential or numerical order of notes in the musical scale through a given number of octaves. Thus, in this block diagram, means are disclosed for producing from three full octave sets of tone generators for an instrument whose keyboard has an octave range of five octaves, the frequencies being, say, from 65.4- to 123.4- cycles per second produced by generators in block A to 1046.-!- to 1975.-lcycles per second produced by generators in block E. By increasing the number of resistive output paths from a respective tone generator, each generator may serve more than a single keybroad and also a pedal keybroad as will be readily understood.

All playing-key switches in each form of my invention are biased to open circuit conditions and adapted to be close-circuited when depressing said keys. Because allowable space does not permit showing the keys at Fig. l, it is understood that the arrangement will be as shown at Fig. 2.

The generators shown in the accompanying drawings may be 12AU7, 6SL7, 6SN7 or 12AX7 vacuum tubes or equivalent devices that are designed and adapted to produce complex waveforms of audio signals of given fundamental frequencies. As operability of my invention makes necessary the use of a complex wave having a first harmonic component reference herein to equivalent devices as tone signal sources shall be construed to mean a device producing a complex waveform composed of `a fundamental and a long series of upper partials or harmonics lof the order of 2n, 311, 4u, Sn, etc. to the fundamental n. Generators or devices producing sawtooth waves are well adapted to serve every purpose of my invention, including the production of simple waveforms from complex wave forms as well as use of complex waveforms in the timbre system of the instrument, for producing a great variety of other complex waveforms characteristic of the tone qualities of different musical instruments.

In the embodiment of my invention shown at Fig. l, the objective is the production from complex waveforms produced by lower octave generators simple waveforms for notes a full octave higher than said complex waveforms. Thus, in addition to timbres produced from said complex waveforms there is available from the instrument, frequencies of sensibly sinusoidal pattern which, `as compared with the frequency range of notes C5-BS=523.[-987.-|- cycles per second, covers the range `for notes C6-B6=1046.-l-1975.-lcycles per second.

What I claim as my invention is:

l. A musical instrument comprising an electrical generator producing an output tone signal comprising a fundamental component of given note frequency and a component the frequency of which is the octave thereof, an electroacoustic output system, and a circuitry interconnecting the generator to the output system via separate output paths in at least one thereof is a band pass filter of the type passing to said system only the octave component of said signal.

2. A musical instrument comprising an electrical tone generator producing an output tone signal comprising frequency components n and 2n, an electroacoustic output system, a first circuitry interconnecting the generator `to the output system via a band pass filter of the type passing thereto only the frequency component n, and a second circuitry connecting the generator to the output system via a band pass filter of the type passing only the frequency component 2n to said system.

3. A musical instrument as set forth in claim 2 in which the first circuitry and the second circuitry are each thereof provided with an electric switch operable by a depressible key for selectively controlling passage of said frequency components to said output system.

4. A musical instrument comprising at least two electric switches each selectively operable by a respective vdepressible key of the same' note letter at octave separation, an electrical generator producing an output signal comprising frequency components n and 2n, an electroacoustic output system, and a circuitry including' said switches interconnecting the generator lto said system via a `band pass filter system `of the type to pass to said output system frequency component n upon depression of one of the keys and similarly to pass to said system frequency component 2n upon depression of the other key.

5. An electrical musical instrument comprising, electrical generators each generator producing an output tone signal comprising a fundamental component of the frequency of a preassigned note of the equal tempered scale and a component the frequency of which is the octave of said fundamental component, an electro-acoustic output system, a band pass filter system including a circuitry interconnecting the generators to said output system via said filter system, said filter system being of the type adapted to pass only the fundamental components to said output system, and a circuitry including a band pass filter system interconnecting said generators -to said output system, said second named filter system being of a type adapted to pass to the output system only the octave components of the produced signals.

6. A keyboard musical instrument employing the equal tempered scale, an electroacoustic output system, generators respectively producing output electric signals comprising frequency components n, 2n, Sn, 4n, Sn, etc, and a circuitry interconnecting the generators to a filter system, said filter system connected to said output system and being of a type adapted to pass to said output system only the frequency components 2n of said signals.

7. A musical instrument employing the equal tempered scale, said instrument comprising, an electroacoustic output system, twelve electrical tone generators, each generator producing an output signal comprising a fundamental component of the frequency of one of the notes of a given octave of said scale and at least a component the frequency of which is the octave of said fundamental component, consecutive octaves of playing-keys and a circuitry interconnecting the generators to the output system and including a wave filter system for transmitting to the output system only the fundamental components of said signals when playing the keys of one of said octaves of keys and for transmitting to said output system only the octave components of said signals when playing the keys of the other octave thereof.

8. A musical instrument employing the equal tempered scale, said instrument comprising twelve electrical generators respectively producing output tone signals for a given octave of notes of said scale, said signals each comprising in addition to a fundamental component of given note frequency a component which is the octave thereof, an electroacoustic output system, a circuitry interconnecting a first group of said generators to the output system via a band pass filter of the type adapted to pass to said output system only the fundamental components of the output signals from said first group of generators, and a circuitry interconnecting a second group of said generators to the output system via a band pass filter of the type adapted to pass to the output system only the fundamental components of the output signals from said second group of said generators.

9. A musical instrument as set forth in claim 8 in which there is combined with said generators means for utilizing the octave components of the produced signals to provide frequencies for an octave of notes sequentially related to said given octave, said means comprising a circuitry interconnecting the generators to the output system by a band pass filter system of the type adapted to receive said signals and pass to the output system only the octave components thereof.

l0. A keyboard musical instrument employing the equal tempered scale, an electroacoustic output system, generators respectively producing output tone signals comprising frequency components n, 2n, 311, 4n, Sn, etc., and a circuitry including a band pass filter system of the type adapted to pass to the output system only the frequency components 2n of 'said signals.

1l. A musical instrument employing the equal tempered scale, electrical generators producing tone signals each composed of a fundamental component of the frequency of one of the notes of a given octave of said scale and a component the frequency of which is the octave of said fundamental component, a keyer circuit from each generator, each keyer circuit having a switch operable by a depressible key, an electroacoustic output system, a bus bar interconnecting a preassigned first group of said switches to said output system by a band pass filter of the type adapted to pass to the output system only the fundamental components of signals from generators common to said preassigned first group of switches, and a bus bar interconnecting a preassigned second group of said switches to the output system by a band pass lter of the type adapted to pass to the output system only the fundamental components of signals from generators common to said preassigned second group of switches.

l2. In a musical instrument of the class employing at least one active of electrical generators producing tone signals each thereof composed of frequency components n, 2n, 3ft, 411, Sn, etc., the combination therewith of means for utilizing frequency components 2n of the signals to provide an octave of frequencies in sequential relation to frequency components n of said signals, and an electroacoustic output system, said utilizing means comprising keyer circuits connecting the generators to said output system via a band pass filter system of the type adapted to pass to said output system only the components 2n of said signals. y

13. In a musical instrument of the class described, a depressible playing-key, first and second switches adapted to be concurrently operated by said key, an output system, an electrical generator producing a tone signal composed of frequency components n, 2n, 3u, 4n, 5u, etc., said generator connected to the output system by a keyer circuit and to the aforementioned first switch, a band pass filter system connecting said switch to the output system, said filter system being of the type to pass only the frequency component 2n to said output system, a second electrical generator producing a signal composed of frequency components n, 2n, 3n, 4n, Sn, etc. in which component n is two octaves higher than component n of the signal produced by the first named generator, said second named generator connected to the output system via the aforementioned second switch to transmit to the output system all components of the signal produced by said second named generator.

14. In a musical instrument of the class described, first, second and third sets of playing-keys respectively indicative of three consecutively related octaves of notes of the equal tempered scale, an output system, electrical generators connected by respective keyer circuits to the output system by switches operated by respective keys of the first set thereof, electrical generators connected to the output system by switches operated by respective keys of the third set thereof, each generator of the first and second named sets thereof producing a signal composed of frequency components n, 2n, 3ft, 411, Sn, etc., and means including a wave filter system the switches operated by the second set of keys for passing to the output system only components 2n of the signals produced by the first named generators and all components of the signals produced by the second generators to provide signals in which said components 2n of the signals produced by the first generators are the fundamental components ya; v

9 for the second octave of notes of the aforementioned three consecutively related octaves of notes.

15. In an electrical musical instrument, twelve electrical generators each thereof producing an output signal composed of a fundamental component of given note 5 frequency and at least a component whose frequency is 'the octave thereof, and two band pass filters each thereof connecting the generators to the output system, each filter being of a type adapted to pass to the output system only lo the fundamental components of a preassigned group of the produced signals.

References Cited inthe file of this patent UNITED STATES PATENTS Kendall Mar. 24, 1925 Carlson Sept. 15, 1931 Vierlng Oct. 31, 1933 Williams Jan. 3, 1939 Koehl Dec. 15, 1942 Rientra June 29, 1943 Hanert et al May 23, 1950 Hammond Aug. 12, 1958 Schreiber Oct. 6, 1959 

